Process for sulfonation of organic compounds



Oct. 23, 19,51 K, F|NCKE 2,572,605

PROCESS FOR SULFONATION OF' ORGANIC COMPOUNDS Filed April 1, 194e JOHN K7 FmK'E JNVENTOR.

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Patented Oct. 23, 1951 PROCESS FOR SULFONATION F ORGANIC COMPOUNDS John K. Fincke, Dayton, Ohio, assignor to Monsanto Chemical Company, St. Louis, Mo., a

corporation of Delaware Application April 1, 1948, Serial No. 18,448

6 Claims.

This invention relates to a process for sulfonating organic compounds.

An object of the present invention is to provide a process for sulfonating organic compounds which is capable of producing sulfonated or polysulfonated organic products. A further object is to provide a process for carrying out the sulfonation reaction substantially instantaneously.

'I'he present invention consitutes an improvemet upon the process for sulfonating organic compounds involving the use of sulfur dioxide as a solvent and SO: as the sulfonating agent. The present process can be carried out in relatively simple equipment and at a high rate of throughput.

In prior processes it has been proposed to carry out sulfonation in liquid sulfur dioxide by indirectly precooling streams of the sulfonating agent and the material to be sulfonated, combining the streams in a zone at sub-atmospheric temperatures, then flowing the stream into a second zone at a temperature higher than the first zone and then diluting or mixing the product with water in order to stop the reaction.

According to my invention, sulfonation is accomplished substantially instantaneously by mixing together a stream of liquid SO2 containing a dissolved organic material which contains at least one grouping of the type: -CH=CH-, and a stream of liquid SO2 containing dissolved S03. The streams are mixed together in a mixing zone comprising preferably a short, tubular nozzle and then sprayed out into a chamber maintained at substantially atmospheric pressure. I have found that when operating in this manner the pressure drop across the spray nozzle is at least 40 pounds Der square inch. As a result of the exothermic reaction heat generated by the sulfonation reaction, evaporation of an equivalent amount of the liquid SO2 occurs in the nozzle, the formation of gaseous SO2 in this manner accounting for the observed large pressure drop therein. The resulting mixture of sulfonated product and vaporized SO2 leaving the nozzle at high velocity sprays into the collection chamber, which is designed to separate the iinely divided sulfonated products from the vaporized gaseous SO2. Any liquid SO2 leaving the nozzle will evaporate in the collection chamber and will lower the temperature thereof, but will not materially afl'ect the nozzle temp'erature. Both products, namely, the sulfonate'd organic product and the vaporized sulfur dioxide may thereafter be recovered in any suitable manner.

The pressure drop across the nozzle when the sulfonation reaction takes place in the nozzle is at least 200 times and may be as high as 500 times that observed for the same mass flow of liquid. The pressure drop depends upon the rate of evaporating SO2 which in turn depends upon the heat of sulfonation and rate of reaction of the hydrocarbons treated and to a lesser extent upon the degree of dilution of the reactants. The temperature of sulfonation, which may be controlled by the amount of SO2 used as solvent for the reactants, should be at least 20 C. and not substantially in excess of 75 C. By using smaller proportions of solvent SO2, the temperature of `suli'onation will be higher than when using larger quantities and vice versa. Except as explained above, the proportion of SO2 present during the reaction is not critical as far as the reaction itself is concerned. However, as stated, by varying the proportions of liquid SO2 used as the solvent the temperatures may be varied within the range indicated.

By reason of the ne state of subdivision of the sulfonation product leaving the nozzle, any liquid or gaseous SO2 in the product is rapidly and completely separated and removed therefrom. Y

As contrasted with previous processes, the present process of sulfonation takes place under adiabatic conditions; in other words, there is no gain or loss of heat to the system. The reaction takes place at temperatures of at least 20 C., but below C., and is completed as far as it is possible to ascertain in the space of time required for passage of the material through the short spray nozzle.

By means of the present invention it is possible to sulfonate any hydrocarbon which is soluble in liquid sulfur dioxide at room or at slightly elevated temperatures and which contains at least one group of the type: -CH=CH. The hydrocarbons may be either aliphatic or aromatic, or mixtures of these compounds. Specific compounds which contain the above grouping and which may be treated by my process are the following: benzene, naphthalene, anthrazene, biphenyl, toluene, ethylbenzene, dodecyl benzene, alkylated naphthalenes, alkylated anthracene, or alkylated biphenyl, etc. Aliphatic hydrocarbons may be any olefin such as ethylene, propylene, butylene, isobutylene, amylene, octene, decene, dodecene, tetradecene, hexadecene, octadecene, etc. Oleiins containing more than one unsaturated grouping may also be treated by the hereindescribed process.

We have found that the S03 combines substantially quantitatively with the unsaturated grouping in the molecule and that it is possible to introduce as many S03 groups as there are replaceable hydrogens present in the groups of the type: -CH=CH- present in the molecule. In order to do this, it is necessary only to proportion the SOa present in the sulfur dioxide liquid stream entering the mixing nozzle so as to contain the number of molecules of S03, which it is desired to introduce into the organic compound to be sulfonated.

As will be noted above, the hydrocarbons which may be sulfonated are characterized by possessing the group: -CH=CH- in the molecule. This group may be a part oi.' an olen'molecule or it may be a part of an aromatic ring. The aromatic sulfonioacids, upon neutralization by alkalies, will consist of the aromatic alkali metal sulfonates. The olefinic products, upon neutralization with an alkali, will consist of the alkane hydroxy alkali metal sulfonates.

'I'he process is carried out by preparing separate solutions of sulfur trioxide in liquid SO2 and of the hydrocarbon to be sulfonated dissolved in liquid SO2. The solutions are stored in pressure vessels under a pressure corresponding substantially to the vapor pressure o! the respective solutions. From the pressure vessels the solutions are withdrawn by means of suitable pipes which connect with a nozzle of relatively short length. The solutions owing into the nozzle become intimately mixed, sulfonation of the hydrocarbon takes place and heat of reaction is thereupon liberated. The liberated heat causes vaporizetion of the S01 within the nozzle. The large volume of gas liberated within the nozzle causes a pressure drop, which is considerably in excess ofthe pressure drop which is observed in the case oi' sulfur dioxide solutions owing through the nozzle. The pressure drop across the nozzle has been found to be at least 40 pounds per square inch and usually less than 100 pounds per square inch.

'Ihe mixture of gaseous SO2 and liquid sulfonation product leaving the nozzle is collected in a gas-liquid separating chamber operating at substantially atmospheric pressure. The vaporized SO2 being water-free is economically recovered,

compressed and liquefied without further puri' cation for reuse in the process. The organic sulfonic acid is neutralized with caustic alkali to produce the alkali metal salts of the corresponding sulfonic acids.

Reference is made to the single ligure of the drawing showing apparatus suitable for carrying out the present process. Referring to the drawing, numeral I indicates a Ytank suitable for containing a sulfur dioxide solution of sulfur trioxide. Tank 2 contains liquid sulfur dioxide. Tank 3 contains the hydrocarbon to be sulfonated. Tanks I, 2 and 3 are supported upon scales l, 5 and 6 so that the contents of the tank may from time to time be weighed. Tanks I and 2 are provided with pressure gauges 1 and n, respectively. and also with connections 9 and I0 for introducing linuid SO2 from pipe II. Tanks I, 2 and 3 are provided with bottom outlets and valves I2, I3 and Il. respectively. for controlling the ow of the contents thereof into pipes I5. IB and I1. respectively. The liquid sulfur dioxide containing dissolved S03 flowing through pipe l5 passes through flow meter I6, then through pipe I! and enters mixing nozzle 20. Likewise. the flow of liquid SOv in pipe I6 passes through flow meter 2I into nipe 22.

The hydrocarbon in tank 3 flows by means of pipe I1 into pump 39. whereby it is forced through pipe 23 into flow meter 2l and pipe 25. The respective liquids flowing in pipes 22 and 25 are combined in pipe 26. wherein the hydrocarbon dissolves in the liquid sulfur dioxide forming a solution thereof. Pipe 26 connects with nozzle 20.

Nozzle 20 is contained within chamber 21 which may be an empty tank of relatively large volume or preferably a tower provided with a packed section 28 consisting of Raschig rings or other suitable packing material. The ends of the tower are closed by means of flanges 23 and 30. An exit for liquid sulionation product is provided at 3| and a gas exit is provided at 32. Pipe 33 connects with an additional liquid-gas separator 3l also provided with liquid outlet 35 and gas outlet 36. The sulfonated product is withdrawn mainly by means of pipe 3| with usually a small amount being recoverable at the outlet of pipe 35. The vaporized SO2 leaving gas separator 3l by means ol.' pipe 36 may be compressed and liquefied by means not shown and returned as liquid sulfur dioxide to pipe II for reuse in the process.

For control purposes a manometer 31 is provided for indicating the pressure in collecting zone 21. A thermocouple 36 is also provided with its junction adjacent nozzle 20 for indicating the temperature of the nozzle and the contents therein. i

The process may be illustrated by the following examples:

Example 1 Benzene sulfonic acid-The apparatus shown in the drawing was utilized, the nozzle 20 being a 0.037" I. D. tube. 0.5 long. A

Sufficient S03 is dissolved in liquid SO; in tank I to form a 30% by weight solution. Benzene is added to tank 3 and liquid SO2 is added to tank 2. The flow of the SO2-SO: solution from tank I is adjusted to the benzene ilow from tank 3 so that slightly more than one mole of SO: is supplied to nozzle 20 for each mole of benzene entering the nozzle. The amount of SO: from tank 2 is proportioned to the benzene now so as to give an approximately 50% by weight solution in pipe 26. During the run the temperature of the nozzle is about 25 C. Benzene monosulfonic acid in good yields is recovered from pipe 3|. The temperature at the nozzle 20 was 20 C. to 35 C.

Example 2 Dodecyl benzene mono-sulfomc acid- Sufficient SO; is dissolved in liquid SO2 in tank I to form a 30% solution. Dodecyl benzene is loaded into tank 3 and liquid SO@ is placed in tank 2. 'I'he ow of dodecyl benzene from tank 3 and SO: from tank 2 is adjusted so that the solution in pipe 26 contains approximately 65% by weight of dodecyl benzene. The ilow of the SO2-SO: solution from tank I is adjusted to supply 1.15 moles of SO; to nozzle 20 for each mole of dodecyl benzene supplied by pipe 26 to nozzle 20. The nozzle is of the same dimensions as in Example 1. The temperature measured at the nozzle was 25 C. to 35 C. Example 3 Example 4 Pentasulfonate of dodecyl benzene-The pentasulfonate oi dodecyl benzene was prepared as in Example 2, except that moles of S03 was supplied to nozzle 20 per mole of dodecyl benzene supplied. The dodecyl benzene was supplied as a 58% solution in S02. The S03 was supplied as a 30% solution in SO2. The nozzle temperature was 63 C. The pressure drop across the nozzle was 50 pounds per square inch.

Example 5 Hexadecane hydroIy-sulfonate.-A 25% solution of SC3-S02 was prepared and supplied to nozzle 20 simultaneously with a 50% solution of hexadecene dissolved in SO2. The flow to nozzle 20 was proportioned so that 2 moles of S03 was supplied per mole of hexadecene. The addition product of S03 and hexadecene was recovered from pipe 3 l added to water and then neutralized with caustic soda. The resulting solution of hexadecane sodium-hydroxy-sulfonate was drum dried and recovered as a nely divided, white powder.

'I'he amount of S0: employed should be suflicient to dissolve the reactants. Any S02 beyond that necessary for dissolving the reactants is not critical, since it merely evaporates after leaving the nozzle and can be recovered and reused. Such excess of SO2 has no appreciable effect upon the pressure drop or upon the temperature of the sulfonation reaction. Since the products of the reaction are dry and pure, it is only necessary to recompress and liquify the SO2 in order that it may be recovered.

A calculation of the pressure drop across the nozzle, assuming that the flow remained entirely liquid, gave a value of only 0.20 pound per square inch. The actual pressure drop which is in excess of 40pounds, but less than 100 pounds per square inch, depending upon the heat of sulfonation of the compound involved, is thought to be due to the fact that the SO2 is vaporized in the nozzle.

Example 6 Carbyl sulfate- Ethylene gas is dissolved in liquid SO2 in quantities suicient to form a 25% solution. This solution is fed to nozzle 20 by means of pipe 26. A 30% solution of S03 in S02 is also prepared and fed to nozzle 20 by means of pipe I9. The respective iiows are proportioned so as to supply 2 moles of S03 for each mole of ethylene supplied. The carbyl sulfate is obtained from outlet 3| and may be hydrated by addition to cold water to form ethionic acid. By treating carbyl sulfate with warm water isethionic acid is formed.

What I claim is:

1. In the process of sulfonation wherein a stream of liquid S02 containing dissolved S03 is mixed with a stream of liquid SO2 containing a dissolved hydrocarbon which contains at least one grouping of the type: --CH=CH-, whereby v said hydrocarbon is sulfonated and heat of sulfonation is liberated, the step of ilowing said mixed streams through a nozzle and completely evaporating said liquid S02 within said nozzle solely by means of said heat of sulfonation, whereby said S03 becomes combined with said hydrocarbon at a temperature o! at least 20 C.

2. In the process of sulfonation in which a stream of liquid S02 containing dissolved S03 is mixed with a stream of liquid S02 containing a dissolved hydrocarbon which contains at least one group of the type: -CH=CH-, whereby said hydrocarbon is sulfonated and heat of sulfonation is liberated, the step of flowing said mixed streams through a nozzle into a zone of lower pressure, complete evaporation of liquid SO2 occurring within said nozzle solely by means of said heat of sulfonation, the pressure drop across the nozzle being at least pounds per square inch.

3. In the process of sulfonation in which a stream of liquid S02 containing dissolved S0; is mixed with a stream of liquid SO2 containing a dissolved hydrocarbon which contains at least one group of the type: CH=CH-, whereby said hydrocarbon is sulfonated and heat of sulfonation is evolved, the step of owing said mixed streams into and through a nozzle at a temperature of at least 20 C., wherein complete evaporation of liquid S02 occurs solely by means of said heat of sulfonation and recovering a sulfonation product.

4. In the process of sulfonation in Which a. stream of liquid S02 containing dissolved SO: is mixed with a stream of liquid S02 containing a dissolved hydrocarbon which contains at least one group of the type: -CH==CH, whereby said hydrocarbon is sulfonated and heat of sulfonation is evolved, the steps of mixing said streams and owing the so-formed mixture through a nozzle, wherein complete evaporation of liquid S02 occurs solely by means of said heat of sulfonation and under substantially adiabatic conditions, said mixture thence flowing into a collection zone maintained at substantially atmospheric pressure.

5. In the process of sulfonation in which a. stream of liquid SO2 containing dissolved S0: is mixed with a stream of liquid S02 containing a dissolved sulfonatable hydrocarbon, whereby said hydrocarbon is sulfonated, and heat of sulfonation evolved, the steps of flowing said streams together into a nozzle whereby complete evaporation of liquid S02 occurs solely by means of said heat of sulfonation and without substantial gain or loss of heat by said flowing stream, and spraying said stream into a zone of reduced pressure.

6. In the process of sulfonation in which a stream of liquid S02 containing dissolved S03 is mixed with a stream of liquid S02 containing a dissolved sulfonatable hydrocarbon, whereby said hydrocarbon is sulfonated, and heat oi sulfonation evolved, the steps of flowing said streams together into and through a confined zone without substantial gain or loss of heat by said owing stream, and wherein complete evaporation of liquid SO2 occurs solely by means of said heat of sulfonation, and then spraying said stream into a zone maintained at substantially atmospheric pressure.

JOHN K. FINCKE.

REFERENCES CITED The following references are of record in the ille of this patent:

- UNITED STATES PATENTS Number Name Date Re. 22,548 Brandt Sept. 26, 1944 1,843,012 Bucherer Jan. 26, 1932 2,007,510 Thornton July 9, 1935 2,187,244 Mills Jan. 16. 1940 2,285,390 Brandt June 9, 1942 2,290,167 Datin July 2l, 1942 FOREIGN PATENTS- Number Country Date 539,281 Great Britain Sept. 3, 1941 

2. IN THE PROCESS OF SULFONATION IN WHICH A STREAM OF LIQUID SO2 CONTAINIG DISSOLVED SO3 IS MIXED WITH A STREAM OF LIQUID SO2 CONTAINING A DISSOLVED HYDROCARBON WHICH CONTAINS AT LEAST ONE GROUP OF THE TYPE: -CH=CH-, WHEREBY SAID HYDROCARBON IS SULFONATED AND HEAT OF SULFONATION IS LIBERATED, THE STEP OF FLOWING SAID MIXED STREAMS THROUGH A NOZZLE INTO A ZONE OF LOWER PRESSURE, COMPLETE EVAPORATION OF LIQUID SO2 OCCURRING WITHIN SAID NOZZLE SOLELY BY MEANS OF SAID HEAT OF SULFONATION, THE PRESSURE DROP 